Ubuntu 11.04 Upgrade…won’t boot – GRUB prompt

Aftert upgrading to Ubuntu 11.04 my server would not boot. It looks like there is a bug in the update such that if you upgrade from Ubuntu 10.10 which itself had been upgraded from Ubuntu 10.04, and grub was never reinstalled then you just get a GRUB prompt after bootup.

To fix this you need to manually boot the system using grub commands. Then reinstall grub. For me the following worked

set root=(hd0,1)
linux /boot/vmlinux-2.6.38-8-generic root=/dev/sda1 ro
initrd /boot/initrd.img-2.6.38-8-generic

Once booted then run

sudo grub-install /dev/sda
sudo update-grub

And then it should all reboot nicely

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  1. It’s not working for me. This a VMWare ubuntu updated from 10.10 to 11.04. Upgrade went perfect (no errors). After reboot, just got grub prompt.

    When issuing “linux /boot/vmlinux-2.6.38-8-generic root=/dev/sda1 ro” i get “file not found” error

    any ideas?

    ls command reports: (Linux-swap_1) (Linux-root) (hd0) (hd0,5) (hd0,1) (fd0)

    Disk type in VM is SCSI 0:0


  2. Figured something out…

    set root=(hd0,1)
    linux /mvlinuz-2.6.38-8-server root=/dev/sda1 ro
    initrd initrd.img-2.6.38-8-server

    It then starts booting but then starts throwing a lot of mounting errors.

    sda1 seems to be the boot partition and sda5 is the root, but the filesystem type is reported as LVM2.

    I tried putting sda5 in the linux command above, but still had same kind of errors.

    Using a 10.10 live cd, I tried “grub-install /dev/sda”, but got a permission error. Tried “sudo grub-install /dev/sda” and got “cannot find a device for /boot/grub (is /dev mounted?).

    I cannot mount sda5. It gives me “unknown filesystem type ‘LVM2_member’

    I’m at a complete loss. I guess I may have to do a full install and then import my mysql databases (i did make a backup). mysql is all this linux machine is used for.

  3. Thanks very much for the post. Worked fine for me on an upgrade from 10.10 to 11.04 under VMware Fusion which also ended in a grub prompt.

    All ok now.

  4. Awsome! Thanks for the reply.

    I searched as you suggested about ununtu grub lvm and after reading several pages, I figured out that my root is /dev/dm-0

    I plugged that into the original instructions and it booted perfectly. Then did the grub install and rebooted.. All is good.. THANK YOU THANK YOU.

  5. I having the same problem after upgrading from 10.10 to 11.04 grub> console prompt don’t know what to do next
    VMware Workstation 7.1.5. I am using but unable to figure out bug in it.. So kindly help with regards to this.. Thanks

  6. The above post almost worked for me.

    Before running:
    linux /boot/vmlinux-2.6.38-8-generic root=/dev/sda1 ro

    do this
    ls (hd0,1)/boot

    It will list the names of the files in /boot. My kernel was named differently than in the blog post (vmlinuz, not vmlinux, and had different dash numbers). Same with initrd.img.*. When I substituted the correct kernel and initrd file names, the instructions worked.

    I didn’t have a /dev/sda1, so I feared that might not be right, but I tried it and it worked anyway.

  7. I’m having the same issue. I got as far as what Jim posted. But now the initrd command won’t work. I run:

    set root=(hd0,1)
    linux /boot/vmlinuz-2.6.32-41-generic root=/dev/sda ro
    initrd initrd.img-2.6.32-41-generic

    And I get
    “Error: invalid file name `initrd.img-2.6.32-41-generic’.”
    Even though it’s listed when I run ls (hd0,1)/boot
    Any ideas? I’ve tried setting to “sda1” and using the other initrd and vmlinuz listed


  8. Oops forgot the /boot in front of initrd.img. However, when boot is pressed it’s followed by scrolling gibberish. Am I toast at this point? This is on a VM

  9. ok one of the kernels worked…just needed a little patience on one of the scrolling gibberish screens. 🙂

    However, it first booted to an initramfs prompt. I ran reboot and then it came back to the illustrious grub> prompt. Then I switched the path to disk to /dev/sda1 instead of sda and that worked like a charm. So the sda does matter. Just so you know.

    Have a nice day.

  10. Thankyou thankyou thankyou!
    Another day of my life wasted on Ubuntu is finally sorted.
    I need to learn “just say no” to upgrades in future for the sake of my sanity (and my wife!).
    I had the same problem with Linuz vs Linux but the ls command worked a treat.
    Thanks once again!

  11. You are amazing!

    Was running ubuntu in virtualbox, and OK’d some sort of “partial” upgrade of ubuntu without thinking.

    Then next time I started up, virtualbox wanted to upgrade too, so I OK’d that too, and started my virtual machine…

    And then all was broken and I got sad because of this unfamiliar “grub” prompt with no boot options 🙁 I had no clue and no idea even which upgrade might have caused the problem. Was getting ready to remove the ubuntu and make a new one, when I found your instructions.

    Which worked perfectly, hooray!

    For other people like me who have no idea how to use grub:

    tabbing gives lists of possible files (so linux /boot/tab will give you a list of good suspects for what you want here).

    Also, like Jim, I didn’t see an “sda1” listed, but typing it still worked.

    Time wasted looking for a solution at ubuntu and virtualbox – lots. Time saved because I don’t have to reinstall my programs and perl modules on a new virtual machine – lots.


  12. Thanks for this post, Rob. I am using Ubuntu version 12.04.1 as a virtual machine on VMware, host machine runnnig Windows 7. I had the same issues of vmlinuz instead of vmlinux and numbers, but also the first command root=(hd0,1) didn’t work for me, instead I pressed tab after “hd” and it showed (hd0,msdos1), which worked fine.

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